1. Technical Field
The present invention relates to network management techniques for reducing power consumption of a vehicle-mounted network system.
2. Related Art
A vehicle includes a plurality of electronic control units (ECUs) for controlling devices mounted in the vehicle, where the ECUs are connected to a communication bus to form a vehicle-mounted network system. A partial networking technique for reducing power consumption of such a vehicle-mounted network system, as disclosed in Japanese Patent Application Laid-Open Publication (Translation of PCT Application) No. 2005-529517, disables some of the ECUs which are unnecessary for system control, depending on circumstances, thereby putting them in a low power consumption state (i.e., a sleep mode).
In the partial networking technique as set forth above, each of the plurality of ECUs includes a transceiver. The transceiver of each ECU has to be always on so as to receive an activation signal via the communication bus even in the sleep mode, which allows the ECU in the sleep mode to return to a normal mode of operation (i.e., a wake up mode) on receipt of the activation signal. Thus, the ECUs continue to consume some power even in the sleep mode. In addition, there is a disadvantage that use of the transceiver supporting the partial networking in each of the plurality of ECUs leads to increased power consumption during the sleep mode.
In consideration of the foregoing, it would therefore be desirable to have network management techniques for reducing power consumption of a vehicle-mounted network system.